Electric lamp



June 4,1940. H. J. sPANNER ELECTRIC LAMP Filed. Oct. 23, 1936 2SheetsSheet 1 INVENTOR A s M N J? I T J A M 2 Sheets-Sheet 2 H. J.SPANNER ELECTRIC LAMP Filed Oct. 23, 1936 llllll June 4, 1940.

INVENTOR HANS I SPAN/VE'R /7 y v ATTOR Y5 Patented June}, 1940 UNITEDSTATES PATENT OFFICE 2,203,550 ntnc'rmc LAMP Hans J. Spanner, Berlin,Germany Application mm 23, 1930, Serial No. 107.190

' 16 Claims. (01. rye-1 This invention relates to gaseous electricaldischarge devices and especially to those in which charge starts so thatthe voltage of the discharge is substantially increased thereby. Moreparticularly this invention relates to a combination of such electricaldischarge device with a radiant series resistance.

This application is a continuation in part of my prior applicationsSerial No. 397,429, filed on October 4, 1929, Serial No. 558,148,filedAugust 19, 1931, Serial No. 643,502, filed November 19, 1932 nowPatent #2991363, Serial No. 744,206, filed September 15, 193i, andSerial No. 51,390,

filed November 25,1935.

One of the problems of eiiicient use of gas discharge devices as sourcesof illumination is the loss of energy in the baliasting device. This isparticularly true in D. 0. operation or in other cases where aresistance is used rather than a reactance. It has been suggested touse. resistance devices capable of giving useful radiation and therebyto utilize some of the energy dissipated in the ballasting resistance.An important obstacle has stood in the way of the complete success ofthis suggestion, namely, that the gaseous discharge devices are subjectto substantial fiuctuation in voltage drop with variations in conditionsof operation and normal variations in line voltage, with the result thatit is difilcult to design a ballasting resistance device which canoperate as an eflicient source of useful radiation without beingsubjected at times to seriousoverloading such as would reduce its usefullife.

This difl'iculty is especially acute in the case of the so-called highpressure vapor lamps in which the pressureand the voltage in the lamprise substantially afterthe discharge is started. With such lamps iftheballast resistance is efficiently designed for normal operation it will,

under ordinary circumstances, be seriously overloaded during the initialstarting period before the pressure has reached its normal operatingvalue.

Accordingly, it is an object of the present invention to provide acombination of a radiant discharge device and a radiant baliastingresistance in which the resistance is protected against over-load andthe energy which otherwise would tend to deteriorate the resistanceduring the over-load condition is utilized for regulating the operationof the discharge device, e. g., by evaporating mercury.

Another object of the invention is to provide a vapor discharge device,and especially a high pressure vapor discharge lamp, in which means isprovided for hastening the heating-up period during which the pressureis increased to its 5 normal operating value.

Another object ofthe invention is to provide a combined gaseousdischarge and incandescent light source in which the deficiency of thegaseous discharge spectrum are made up by radiat'lon from theincandescent source.

In the accompanying drawings are shown several preferred embodiments ofmy invention and certain modifications thereof. These are not intendedto be exhaustive or limiting of the invention, but are chosen forpurposes of illustration in order that others skilled in the art mayfully understand the principles of the invention andtheir application inpractical use, and that they may have no difiiculty in applying the inventionin numerous other forms according to the requirements of variousconditions and special problems.

Fig. 1 is a view partly in longitudinal section of a typical highpressure vapor lamp for general illumination purposes havingincandescent filament therein according to my invention.

Fig. 2 is a view in cross section taken on line 2-2 of Fig. 1.

Fig. 3 is a view in cross section showing a lamp 3( similarto that ofFig. 1, but having special means for protecting the filaments againstoverload.

Fig. 4 is a view partly in side elevation, partly in vertical section ofanother embodiment of my invention. Fig. 5 is a view in perspective ofstill another embodiment of my invention.

Fig. 6 is a fragmentary view similar to the upperportion of Fig. 5 butshowing another modification.

Fig. 7 is a view partly in vertical section and partly in side elevationof another embodiment of my invention; and t Fig. 8 is a fragmentaryview in axial section of anotherembodiment of my invention.

Referring first toFig. 1, I have shown there a lamp for generalillumination purposes. An inner envelope Iii serves to enclose theatmosphere in which theelectrical discharge takes place between thefixed solid electrodes ll mounted on the lead-in wires l2.

This inner envelope I0 is supported within an outer jacket l3 bymeans ofa framework l5-IE the construction of which is clearly shown in thedrawings and which is advantageously made of 'nickel or other resilientmaterial, so asto avoid breakage of the envelope l during shipment, etc.

'As'will be observed from the drawings, the

to one of the contacts on the base 2l, e. .g., a

standard Edison Mogul base.

The upper part l6 of the mounting frame is connected by the flexibleconnection 22 to the lead-in wire l2 of the upper electrode and isshaped so that it is engaged between the upper domed end of the jacketl3 and the upper end of the envelope l0. 7

The connections l8 and 22 are not essential and the lead wirescan bewelded directly to" the frame parts l and I9, but I prefer by means ofthese flexible connections to relieve the seals between the envelope Illand the lead-in wires I! of any possible strain which may result fromdirect welding to the frame.

As will be observed the longitudinal wire members of the frame portionsl5 and I6 extend, between the insulating discs l'l, along the sides ofthe envelope iii. In order to give further support and also to provide acapacity along the side of the envelope to assist in starting (asdemembers lS-IB and connections "-42 and 22-42 to the electrodes 1!, andthere serves to break down the gas filling between the electrodes andestablish a discharge. This discharge in turn heats the electrodes ll,converting the initial discharge to an arc. At this point the dischargeoperates with a minimum voltage, and a maximum current; and a maximumloading is, therefore, imposed uponv the filaments 25, with acorresponding tendency to overheat these filaments to a brilliant whiteincandescence. It is.

an advantage of my combination lamp that at this stage, while theillumination from the discharge is at relatively low intensity, theintensity of the incandescent filaments is substantially increased, andfurthermore the color from the filament is substantially white. Withoutspecial precaution to protect the filament, however, there wouldbeserious danger of destructive overheating at this stage and consequentburning out of the filaments. It is an advantage of the constructionshown,'however, that these filaments are in intimate heat-exchangerelation .to the envelope l0 which, at this stage of operation, is 1relatively cool. There is,'therefore, a rapid transfer of heat byradiation and convection from the filament to the envelope, which hasthe double advantage of protecting the filament against over-heating andof; hastening the evaporation of the vaporizable filling within theenvelope Hi.

In order to give full efiect of this heat trans fer, a suitableconvection gas is provided within the jacketl3. This may be an inert gassuch as has been used heretofore in incandescent lamp scribed andclaimed in a prior application Serlak bulbs. g" argon, nitrogen, etc" ormixtures of No. 744,206) these are brought as close as posible to thewall of the envelope l0, preferably without quite touching it, so as toavoid.possi ble contact of the base 2| to the lower electrode and theshell of the base to the lower portion ii of the frame, but that directconnection from the base to the upper electrode is made only through thefilament wires 25, which are hung in zig-zag arrangement between thelongitudinal members of the frame is and I6, and are supported thereonby the fine looped wires 26 welded to the frame members, or by weldingdirectly to, or winding around the frame members. I It will be observedthat this arrangement of the filament provides numerous parallel pathsfor passage of the current between the frame portions l5 and It. Thesize of the filament wires is designed so that with all of these pathsoperating in parallel and with the envelope lfl'at full operatingtemperature, these filaments will be at low incandescence, giving averyred' radiation. The envelope i0 is filled with a starting gas suchas argon, neon, etc., at low pressure and with a supply ofa'vapo'rizable material such as for example, mercury in amountsufllcient when vaporized to increase the resistance of the dischargepath so that the voltage drop within the envelope l0 between theelectrodes II is substantially increased after starting of the dis--charge. The jacket I3 is filled with a suitable gas inert with respectto the filament, e. g., argon, or nitrogen or hydrogen, or mixtures ofsuch gases as more fully described below.

In the operation of this device a voltage is impressed upon the lampacross the terminals of the base and conducted, substantially withoutdecrease, through the filaments 25 and the frame such gases, .atpressures sumciently high to avoid any short-circuiting discharge acrossthe filament 3!, e.'g.,- about one-half atmosphere, but I have found itparticularly advantageous to use a gas having a'high heat transfercapacity. Hydrogen gas is particularly suitable for this purpose,probably because at temperatures below those at which destruction of thetungsten filament occurs and above the temperatures of the filament innormal operation, the hydrogen is decomposed from the molecular state tothe atomic state with absorption of large amounts of heat from thefilament which are carried to and yielded up to cooler surfaces, as forexample the surface of the envelope II. The expansion in volume anddecrease in density of the gas due to this dissociation also facilitatethe convection circulation of gases over the filament and the envelope.This arrangement,- therefore, has, the known action of the so-callediron-hydrogen" resistance, with the additional advantage that its heatis utilized for rapidly bringing the arc lamp to operating temperature.Obviously the overloadprotection action of the hydrogen atmospherearound the hot resistance wire can be utilized elsewhere than in theconcentric jacket for apart or all of the ballast for the arc lamp.

Although an atmosphere of pure hydrogen may be used in the jacket I3, Iprefer to use a mixture of hydrogen and an inert gas, for examplehydrogen and argon.

In the above I have referred to theuse of a convection gas in the jacketat a pressure such that no short-circuiting discharge will occur acrossthe filament. In one embodiment of my invention, however, such adischarge may be taken advantage of. to protect the filaments againstoverloading. Thus if the gaseous filling in the jacket is at a pressureregulated to break down at the voltage at which the maximum temperatureof the filament is reached the gas itself will serve as a protection forthe filament. In such case the initial operation is exactly as describedabove, namely the full voltage is imposed through the filament upon theelectrodes, a break-down occurs within the envelope and the initialdischarge is converted into an are by heating of the electrodes. At thispoint, however, the voltage within the envelope has become so low andconsequently the voltage imposed on the filament is so high that theheated filamen will cause substantial ionization of the gas aroun it,and a breakdown of the gas will occur along the filaments 25 in parallelwith the filament current. This dischargehowever, can continue only solong as the discharge in the envelope ll) remains at low voltage and solong as the filament remains hot enough to provide the necessaryelectron emission. As soon as the voltage consumption in the maindischarge increases due to the evaporation of the mercury and thetemperature of the filament is consequently decreased the remainingvoltagewill be insufilcient to sustain the external discharge, andconsequently the further operation of the lamp at normal operatingtemperature will continue exactlyas in the case described above.

It will. be understood by those skilled in the art that .where adischarge is to be permitted 30, in parallel to the filament 25 thismust never be permitted to become an independent discharge, but must atall times depend upon the heating of the filament so that, upon coolingof the filament whether due to short-circuiting bythe discharge itselfor to the increased voltage requirement of the main discharge theelectrode drop of the .short-circuiting discharge will rise above thevoltag. drop of the filaments when carrying the entire current and thusthese auxiliary short-circuiting discharges will be extinguished. In nocase can the ballasting effect of the resistances be completelydestroyed by the short-circuiting discharges. In Figs. 1, 4, 5, 6 and '7the unit may be made self-contained for operation from constantpotential circuit,.whereas with the use of parallel discharges asdescribed as an alternative of Fig. 1, or parallel filaments as in Fig.3, additional ballast outside the lamp would obviously be used in theoperation as described.

The vaporizable filling within the envelope I0 is preferably chosen togive an emission spectrum which is strongest in the violet, blue, greenand yellow-green and preferably one which is fairly complete in thatrange so as to complement the low incandescence of the filament whichradi ates mostly in the red, orange and orange-yellow;

and it is furthermore preferably chosen so as to raise the envelope IDto a relatively high temperature at which it will help to sustain theincandcscence of the filament by reducing the cooling effect ofradiation andconvection. Both ofthese effects are produced with greatestadvantage by a. high pressure mercury filling e. g., of one or moreatmospheres of pressure during normal operation.

' In Fig. 3, I have shown another device adapted to provide furtherprotection for the filament during the initial heating-up period, whilethe voltage requirement of the main discharge is low.

In In this case a bimetallic, thermostatic contact 30 is secured to thedisc I'Ia corresponding to the lower disc I! of Fig. 1 and is connectedto the frame l5 as shown.

A fixed contact strip 3| is secured at ill to the 7 disc "a as shown,andisbowed over the end of the thermostatic strip 3|] so as to makecontact therewith when the thermostat is cool but leave room for thethermostatic strip 30 to move out of contact when it is heated by thelamp. Filament wires 32 are connected from the frame members I6 to abook 33 on the strip 3|. Thus when the lamp is cold and until it hasreacheda temperature at which the increased voltage in the maindischarge will protect the filament wires 25 the filaments 32 areconnected through the strips 30 and 3| and the hook 33 in parallel withthe filament 25 and the size of the filament wires 32 is regulated sothat during the initial over-load period all of these parallel filamentswill be at high incandescence but well below the temperatures at whichburning out of the filament would occur.

. In order that the thermostat 30 may be primarily responsive to thetemperature of the envelope l0 rather than to the temperature created bythe filaments 25 and 32 a tube 34 or other suitable baflle member ispreferably placed over the thermostat 30 to intercept heat transfer fromthe filament while permitting direct inter-change of heat with theenvelope I 0. Ordinarily, however, this will not be necessary if thestrip 30 is welded at one endto the member I5 close beside the envelopei0 and extended therealong on the opposite side of the envelope from thefilament wires 32.

In Fig. 4, I have shown another embodiment of my invention in which theseries resistance filament is enclosed within a separate bulb 40 withinthe jacket l3b. In this case the discharge envelope lllb can be aroundthe incandescent lamp bulb 40 as closely as possible so as to be inheat-exchange relation thereto; but at best this arrangement is lessadvantageous than that described above because the closed bulb 40 tendsto limit the heat exchange between the two. The principal advantage ofthis arrangement is that standard discharge and incandescent lamps canbe combined in a fixture without the necessity of sealing the twotogether, and therefore if the filament should burn out due to over-loadthis can be more readily replaced.

In Fig. 5, is shown another alternative similar to that of Fig. 1 butusing a simpler and less rugged mounting. In this case the filamentwires 25c run longitudinally along the lamp, instead of in zig-zag,between the frame members I50 and lie.

In Fig. 6,1 have shown still another lamp similar to that of Fig. 5, butusing a spiral filament 25d supported by the frame "id at one end of thelamp instead of the parallel longitudinal filament.

Instead of a single vaporizable metal, Imay also use a plurality ofmetals, as for example a mixture of mercury, cadmium and zinc, or amixture of mercury and other higher boiling point metals. This isparticularly advantageous where the incandescent filament is to beoperated at a temperature of maximum practicable efficiency, as forexample where it is protected during the initial starting period by ashort-circuiting discharge or by the parallel or substituted filament asillustrated for example in Figs. 8 and andemciency 'of theincandescent'lamp will be less impaired. This is especially advantageouswhere the lamp is designed to reach equilibrium without totalevaporation of the vaporizable metal. e. g., as described in myapplication, 8erlal No. 558,148, filed August 19, 1931.

In 'Fig. 7, I have shown another device similar to that of Fig. 4, butin this case a special lamp for starting or the lighter filament fornormal operation will be connected in series with the gaseous dischargelamp according to the temperature of the thermostatic switch.

An enclosing jacket lie in this case is not essential but is highlydesirable. Fig. 8 shows a ballast resistance coil 25! surrounding thepump tip 50 at the lowest part of the lamp. The liquid metal collects inthis depression and as soon as the discharge begins is strongly heatedby the resistance coil 25! so that it is very quickly evaporated. I Theresistance 25f may advantageously be only a protecting parallelresistance switched into the circuit only during starting and thuscorresponding to the filament 32 of Fig. 3. Or the heater 25 may be inseries or parallel with other lighting filaments and the tip 50 may beso remote from the discharge that it controls the pressure of at leastthe highest boiling point metal in the tube, lllf. Thus if an overloadcondition occurs this heater will evaporate more metal and withunder-load will allow metal to condense and thereby keep the loading ofthe filaments approximately at the best temperature for life andefiiciency.

I claim:

l. The combination of a radiant electrical discharge device having avaporizable filling therein adapted by vaporization to at least doublethe voltage drop in the discharge device and a radiant ballastresistance therefor, in which the ballast resistance is in heat-exchangerelation to the discharge device such that during initial operation theheat generated in the ballast resistance is utilized to hasten thevaporization of the filling in the discharge device and during theinitial low voltage operation before vaporization of the filling and inother case of overload, the thermal capacity and heat dissipatingcapacity of the dis-' charge device will absorb excessive heat developedin the ballast resistance and protect it against destructiveover-heating.

2..An electrical discharge device which comprises an envelope, a fillingwithin said envelope including a vaporizable material adapted to providea gaseous medium for the discharge and by vaporization to increase thevoltage of the discharge, electrodes spaced therein, lead-in'connections, an incandescent filament connected in series to one of saidlead-in connections, adapted to be heated by the current of thedischarge and positioned outside but in heat-exchange relation to theenvelope a substantially closed jacket enclosing the envelope andfilament, and a heat transfer gas in said jacket which includeshydrogen. 1

3. The combination of a vapor electric discharge device having avaporizable filling adapted by vaporization to at least double thevoltage drop of the discharge device and an incandescent filament inseries therewith in a gas adapted to break down and carry a dischargeacross the filament at a voltage less than sumcient to cause destructiveoverheating of the filament, and the filament and its connections areadapted to sustain such discharge only above the voltage applied to thefilament in normal operation.

4. The combination'of a vapor electric discharge device having avaporizable filling adapted by vaporization to increase the voltage dropof its discharge, an incandescent filament in series therewith, means inparallel to said filament for carrying at least a part of the dischargecurrent during the warming-up period of the discharge while its voltageconsumption is low, and means to discontinue the current through saidparallel means after the warming-up.

5. The combination of a vapor electric discharge device having avaporizable filling adapted by vaporization to increase the voltage dropof the discharge and an incandescent filament in series therewith, andmeans adapted to protect thefilament'against excessive heating byincreased current during the warming-up period of the discharge whileits voltage drop is low in which the means for carrying dischargecurrent during the starting period comprises an auxiliary filament inparallel to the first named filament and a switch therefor responsive toconditions resulting from evaporation of the vaporizable filling adaptedto break the circuit of said auxiliary filament and leave the firstnamed filament in series with the lamp.

6. The combination of a vapor electric discharge device having avaporizable filling adapted by vaporization to increase the voltage dropof the discharge and an incandescent filament in series therewith, andmeans adapted to protect the filament against excessive heating byincreased current during the warming-up period of the discharge whileits voltage drop is low in which the means for carrying dischargecurrent during thestarting period comprises an auxiliary filament inparallel to the first named filament and a thermostatic switch thereforresponsive to temperature resulting from evaporation of the vaporizablefilling adapted to break the circuit of said auxiliary filament, andleave the first named filament in series with the lamp."

7. The combination of an electrical discharge device of the type whichincreases its effective voltage drop after starting of the discharge, a

ballast resistance therefor, a molecular cooling fluid over saidresistance adapted to be decomposed -by heat generated by said resistorand with an endothermic reaction and to recombine at lower temperaturewith liberation of heat of combination and means for holding said fluidover said resistance. a

8. The combination of an electrical discharge device of the type whichincreases its effective voltage drop after starting of the discharge, aballast resistance therefor, an atmosphere of hydrogen over saidresistance and means for holding said hydrogen over said resistance.

9. The combination of a vapor electric discharge lamp having avaporizable filling adapted by vaporization to increase the voltage dropof the discharge and an incandescent filament lamp in series therewith,and means adapted to increase the resistance in series with thedischarge during the warming up period of the discharge while itsvoltage drop is low whereby to protect said filament against overload,said increased resistance being less than will fully compensate for thelower voltage of the discharge whereby the current is temporarilyincreased for heating the discharge lamp and for supplying greaterillumination from the filament lamp.

10. The combination of a vapor electric discharge device having avaporizable filling adapted by vaporization to increase the voltage dropof the discharge and an incandescent filament in series therewith, andmeans adapted to protect the filament against excessive heating withincreased current during the warming up period of the discharge whileits voltage drop-ls low, said protecting means being less thansufilcient to fully compensate for the lower voltage of the discharge,whereby the current is temporarily increased for heating the dischargelamp and for supplying greater illumination from the filament lamp whilethe voltage or the discharge is at its lowest value.

11. A lighting circuit which comprises a source of current, a vaporelectric discharge lamp having a vaporizable filling adapted byvaporization to increase the voltage drop of the discharge and anincandescent variable filament lamp in series therewith, and means forswitching the filament circuit so that the filament effectively in thecircuit during the starting period is adapted to reach incandescence inthe circuit with a higher voltage drop than, that of the filament in thecircuit during normal operation, and the filament in the circuit duringnormal operation is adapted to maintain incandescence with the voltagedrop available to it during said normal operation.

12. The combination of a vapor arc lamp of the type which increases itsvoltage to a substantially predetermined extent by evaporation of alimited supply of vaporizable material, and a plurality of incandescentfilaments connected in parallel with each other and in series with thelamp, each carrying a relatively small part of the total arc currentwhereby any one may become disabled without seriously impairing theoperation of the arc lamp or the other filaments.

13. A lamp comprising in combination a vapor arc lamp of the type whichincreases its voltage by evaporation of a vaporizable material therein,an incandescent filament ballast, and means for supportig saidincandescent filament, which combination is characterized by having afixed body in intimate heat exchange relation to the incandescentfilament substantially throughout the incandescent length of thefilament and having a heat absorbing capacity sufiicient to preventburning out of the filament due'to overloading in the first momentsafter the arc and filament are energized and until the arc voltage hasbeen increased by vaporization of its filling material.

14. A lamp comprising in combination a vapor arc lamp of the type whichincreases its voltage by evaporation of a vaporizable material therein,an incandescent filament ballast, and means for supporting saidincandescent filament, which combination is characterized by having thefilament in intimate heat-exchange relation to the envelope of the vaporarc lamp whereby the heat developed by the filament during the startingperiod is utilized for vaporization of the vaporizable filling insaid-envelope and thereby the heatng up period is reduced and thefilament protected against excessive overheating.

15. The combination of a vapor arc lamp of the type which increases itsvoltage by evaporation of a vaporizable material therein and a seriesresistance connected thereto having a positive temperature coefllcientof resistance, whereby the initial arc current through the lamp 'isgreater due to the lower resistance value of the series resistance thanduring subsequent operation and means for cooling the resistance duringits initial operation, whereby its resistance reniains relatively lowduring the initial heating of the lamp and such heatingis thus hastened.

16. The combination as defined in claim 15, in which at least a part ofthe resistance is in intimate heat-exchange relation with the arc lamp,whereby the heat capacity of the arc lamp dclays the heating up of theresistance value. thus permitting a greater initial heating of the arclamp by overloading the are as well as by heatexchange from the seriesresistance.

HANS J. BPANNER.

